The disclosures herein related generally to skeletal joint surgery and more particularly to an instrument for measuring both the alignment and the flexion of one skeletal member relative to another skeletal member.
Instruments are used to satisfy a surgical desire to accurately measure the angle of a varus or valgus knee and/or to measure the extent of a knee in flexion and extension during a uni or total knee replacement surgery.
It is normal practice for a surgeon to review patient x-rays prior to either a uni or total knee replacement surgery. This review gives the surgeon direction and aids in determining the amount of, if any, angular/alignment correction to establish in the patient""s knee during the surgical procedure.
Although a surgeon may realize how much correction is required, it is sometimes difficult to determine if that degree of correction has been obtained in surgery. Several types of devices are available to determine alignment but few are available to measure alignment before implantation of a knee replacement and then again after the implantation is complete, thus, determining the amount of incremental change.
There are numerous devices of varying complexity that a surgeon may use to measure the degree of deformity in a knee. Devices like a simple Goniometer, which are commonly used to measure angles on an x-ray to more complex surgical devices that are used on the human anatomy. Most instruments will violate the intramedullary canal which is undesirable.
A Goniometer is a dual armed instrument for measuring angles. One arm has a pointer, the other a protractor scale. A pivot, that provides enough friction to stabilize the instrument for easy reading, joins these arms.
Sulzer Orthopedics Inc. offers an Uni-Knee Alignment Checker, part number 6190-00-117, which is a surgical instrument for measuring anatomical alignment of a knee in extension. Other knee systems and orthopedic companies offer a similar type instrument.
Therefore, what is needed is an alignment and flexibility measuring device to accurately measure the angle of a varus or valgus knee and to measure the flexion and extension of the knee during a uni or total knee replacement surgery.
One embodiment, accordingly, provides an instrument which is useful for measuring the xe2x80x9cbeforexe2x80x9d resection alignment of a joint and the xe2x80x9cafterxe2x80x9d resection alignment of the joint, and to also for measuring the flexion and extension of a knee during a uni or total knee replacement surgery. To this end, a knee surgery instrument includes an adaptor having pin apertures formed therein for receiving surgical pins, and also includes adaptor pins extending therefrom. A caliper may be mounted on the adaptor pins and on the surgical pins in a first skeletal member. A rod is connected to the caliper for indicating alignment and flexibility of a second skeletal member relative to the first skeletal member.
A principal advantage of this embodiment is that the instrument and the associated procedure are minimally invasive, provides measurement for varus and/or valgus deformities, provides flexion and extension measurement, provides alignment measurement before and after implantation, and allows an expansive range of measurement.